Before ever starting the truck, sit inside as you do add weight to the truck, leave the door open, just turn the switch on but don't crank or start the truck, (Ya no when you hear the chime and the lights in the Spedo come on.) After a few seconds of turning the switch, you should hear or feal the compessor kick in. It always works on Continental, Town Cars, Marks.
The way ya specify what the truck does, id say try doing this in the moarning after the truck had some shuteye.
Though, you should see the ( Air Ride Off or Check Air Ride light) come on if you shut the air ride switch to off. Even after a drive, the moment you get out and shut the door, you should here a click and a faint sound of air releaving which is the truck lowering back to normal level. ( Like a car with really slow hydrolics movements)